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Killifish Care Sheet

Killifish Care Sheet

Updated on July 28, 2022
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Reviewed by Petco’s Animal Care
Education and Compliance (ACE) Team

Appearance & behavior | Characteristics | Habitat | Feeding | Care | Recommended supplies | Recommended tank mates | Common health issues | FAQs

This care sheet covers a variety of Killifish species, including:  

  • Golden Wonder
  • American Flagfish
  • Lampeye
  • Clown
  • Gardners’s
  • Golden Lyretail
  • Gunther’s
  • Gunther’s Blue

 

Killifish

Overview 

Scientific names: Aplocheilus lineatus, Jordanella floridae, Aplocheilus normani, Aplocheilus annulatus, Aphyosemion gardneri, Aphyosemion australe, Nothobrachus guentheri

Killifish are some of the most colorful species of freshwater fish. Although the name may sound dangerous, the name "Killy" is a Dutch word meaning channel or ditch. This adaptive species is found widespread throughout the world from the tropical and subtropical waters of Southern Europe, Africa, Asia, and North and South America.  Most of these fish are freshwater but there are some species found in brackish and marine environments. Some species of killifish have very short lifespans and are found in temporary pools of water which may only last for a several months before drying up. There are approximately 1,270 species of killifish.

Typical appearance and behavior 

  • Males are territorial, females can be kept in groups
  • Killifish are great jumpers, and a secure cover is recommended
  • Found mainly in freshwater but some species can be found in brackish and marine environments
  • Females are generally a bit larger than the males. 
  • Males are generally a bit to a lot more colorful, depending on the species
  • Killifish are carnivores 

 

Characteristics

Care Difficulty Ranges from beginner to advanced, depending on species
Average Life Span Up to 2 to 5 years when properly cared for, depending on species
Average Adult Size 1–6 inches long, depending on species
Diet Carnivore or Omnivore, depending on species
Minimum Habitat Size 5+ gallons
Water Temperature 68–75°F

Habitat 

Habitat size

Keep in an appropriately sized aquarium for the species selected, which can range from 5 gallons for a smaller species pair, to a much larger aquarium for larger species and community setups. 

Building your habitat

  • Water health 
    • Provide proper filtration to ensure optimal water quality to help maintain health; low to strong water circulation should be provided to mimic the water currents and high oxygen levels found in the killifish’s natural habitat
    • Stable water quality (pH, ammonia, nitrate, nitrite) and water temperature are critical to the health of aquatic life; if you are unsure of your water quality, bring a sample to Petco for free testing
    • An aquatic heater should be utilized to stabilize water temperature, ensuring it does not fluctuate more than 2 degrees in either direction in a 24-hour period
    • Killifish will benefit from the addition of freshwater salt to the aquarium. The specific gravity should be kept at 1.004; do not allow specific gravity to fluctuate more than 0.001 in either direction in a 24-hour period. Some species may prefer a more brackish environment. Always research specific species’ needs prior to purchase.
  • Décor: Provide plenty of space for swimming, as well as plants, rocks or décor for hiding places

Feeding 

A well-balanced killifish diet consists of:

  • Brine shrimp, mysis shrimp, daphnia, bloodworms, tubifex (live, freeze-dried, or frozen), fruit flies
  • Most killifish are carnivorous, but the American Flagfish is an omnivore which will benefit from the addition of some plant-based foods and algae.

Things to remember when feeding your killifish:

  • Feed small amounts two to three times daily, no more than your fish will eat in 1–2 minutes
  • Thaw frozen food before feeding

Killifish care

  • Maintaining great water quality with regular water changes and adequate filtration is important to help keep your killifish healthy
    • Daily: Check filter, water temperature and other equipment
    • Weekly: Test water quality at least once a week
    • Weekly to monthly: Change 10–25% of the total volume of water every 2–4 weeks, or as needed; change filter media monthly
  • Avoid overcrowded conditions, which are a major cause of stress and disease

Where to buy Killifish

Various killifish are available for purchase at Petco online and in-store; availability varies by location. If visiting your local Petco Pet Care Center location, please call ahead to check availability.

Killifish supplies 

Tank mates 

Killifish are generally peaceful and can be kept with community fish of similar size and temperament. Males can be territorial, do not house two males together unless the aquarium is large enough to safely house them together and establish their own territory. 

Health 

Signs of a healthy fish

  • Clear eyes
  • Eats vigorously
  • Good coloration
  • Free of parasites or disease

Red flags (if you notice any of these signs, contact your local aquatic specialist or veterinarian)

  • Loss of color or appetite
  • Spots or fungus on body or mouth
  • Cloudy eyes or pop-eye
  • Listlessness
  • Labored breathing
  • Erratic swimming
  • Weight loss
  • Bloating
  • Frayed or discolored fins

Common health issues

Health Issue Symptoms or Causes Suggested Action
Health IssueFin rot Symptoms or CausesFrayed or disintegrating fins; the base of the fins usually reddens. Suggested ActionImprove water quality; consult your local aquatic specialist or aquatic veterinarian for treatment.
Health IssueBacterial infections Symptoms or CausesCloudy eyes, open sores and/or reddening of the skin. Suggested ActionImprove water quality; add or slightly increase freshwater aquarium salt level; use a commercial antibacterial remedy as directed; consult your local aquatic specialist or aquatic veterinarian for treatment
Health IssueIch Symptoms or CausesWhite spots appear on fins and body; fish rubs against hard objects or swims erratically. Rapid respiration. Suggested ActionQuarantine fish immediately; add freshwater aquarium salt and use commercial ich remedy as directed. Consult your local aquatic specialist or aquatic veterinarian.
Health IssueCottonmouth or Columnaris Symptoms or CausesCottony white growths along the body and/or gills, frayed fins and gills turn brown and necrotic in late stages; caused by bacterial infection. Suggested ActionQuarantine fish; improve water quality; lower aquarium temperature to 72°F to deter bacteria from growing; medicate as directed; consult your local aquatic specialist or aquatic veterinarian for treatment.

FAQs

How long do killifish live?

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Killifish can live from 2 to 5 years when properly cared for. 

What do killifish eat?

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Killifish should be provided with a variety of freeze-dried, frozen, or live brine shrimp, mysis shrimp, daphnia, bloodworms, tubifex and fruit flies.

What fish can live with killifish?

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Killifish are typically peaceful and can live with other appropriately sized and similar temperament fish. Do not house two male killifish together unless the aquarium is large enough to safely house them, providing enough space to establish their own territories.

How many types of killifish are there?

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There are approximately 1,270 different species of killifish.

How big do killifish get?

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Killifish can grow from 1 to 6”, depending on species.

Notes and resources

Ask a Pet Care Center store employee about Petco's selection of products available for the care and happiness of your new pet. All products carry a 100% money-back guarantee.

Because all aquatic life are potential carriers of infectious diseases, such as atypical mycobacterium and salmonella, always wash your hands before and after handling your aquatic life and/or habitat contents to help prevent the potential spread of diseases.

Pregnant women, children under the age of 5, senior citizens and people with weakened immune systems should contact their physician before purchasing and/or caring for aquatic life and should consider not having aquatic life as a pet.

Go to the Centers for Disease Control at cdc.gov/healthypets for more information about aquatic life and disease.

The information on this Care Sheet is not a substitute for veterinary care. If you need additional information, please contact your veterinarian as appropriate.

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